tsarnaevandtamerlantsarnaevwalking towards the finish line with backpacks, a second and crucial piece of video, the fbi says, comes from a surveillance camera mounted on this restaurant. at 2:42, court documents say the still unreleased video shows dzhokhar tsarnaev with a backpack walked towards the scene of a second bombing. at 2:45, he slips his backpack off. still photos show the backpack on the ground at his feet. when the first bomb goes off, the fbi says, the video shows the crowd looking towards the finish line in alarm. but the fbi says tsarnaev virtually alone among the individuals in front of the strauvent appears calm. he walks away, it says, without his backpack, and ten seconds later, the second bomb goes off in the spot where he left the backpack. the fbi says both the marathon bombs were made with pressure cookers and metal bee-bees. they contained hobby fuse similar to this. at the scene of thursday night's shootout in watertown, investigators say they found another bomb and hobby fuse and bee-bees. the fbi says they searched dzhokhar tsarnaev's dorm room and found be